The use of airborne LiDAR (Light Detection and Ranging) as a direct method to evaluate forest canopy parameters is vital in addressing both forest management and ecological concerns. The overall goal of this study was to develop the use of airborne LiDAR in evaluating canopy parameters such as percent canopy cover (PCC) and leaf area index (LAI) for mixed pine and hardwood forests (primarily loblolly pine, Pinus taeda, forests) of the southeastern United States. More specific objectives were to: (1) Develop scanning LiDAR and multispectral imagery methods to estimate PCC and LAI over both hardwood and coniferous forests; (2) investigate whether a LiDAR and normalized difference vegetation index (NDVI) data fusion through linear regression improve estimates of these forest canopy characteristics; (3) generate maps of PCC and LAI for the study region, and (4) compare local scale LiDAR-derived PCC and regional scale MODIS-based PCC and investigate the relationship. Scanning LiDAR data was used to derive local scale PCC estimates, and TreeVaW, a LiDAR software application, was used to locate individual trees to derive an estimate of plot-level PCC. A canopy height model (CHM) was created from the LiDAR dataset and used to determine tree heights per plot. QuickBird multispectral imagery was used to calculate the NDVI for the study area. LiDAR- and NDVI-derived estimates of plot-level PCC and LAI were compared to field observations for 53 plots over 47 square kilometers. Linear regression analysis resulted in models explaining 84% and 78% of the variability associated with PCC and LAI, respectively. For these models to be of use in future studies, LiDAR point density must be 2.5 m. The relationship between regional scale PCC and local scale PCC was investigated by resizing the local scale LiDAR-derived PCC map to lower resolution levels, then determining a regression model relating MODIS data to the local values of PCC. The results from this comparison showed that MODIS PCC data is not very accurate at local scales. The methods discussed in this paper show great potential for improving the speed and accuracy of ecological studies and forest management.

Enhanced understanding of forest stocks and dynamics can be gained through improved forest measurement, which is required to assist with sustainable forest management decisions, meet Australian and international reporting needs, and improve research efforts to better respond to a changing climate. Integrated sampling schemes that utilise a multi-scale approach, with a range of data sourced from both field and remote sensing, have been identified as a way to generate the required forest information. Given the multi-scale approach proposed by these schemes, it is important to understand how scale potentially affects the interpretation and reporting of forest from a range of data. ¶ To provide improved forest assessment at a range of scales, this research has developed a strategy for facilitating tree and stand level retrieval of structural attributes within an integrated multi-scale analysis framework. The research investigated the use of fine-scale (~1m) airborne Light Detection and Ranging (LiDAR) data (1,125 ha in central Queensland, and 60,000 ha in NE Victoria) to calibrate other remotely sensed data at the two study sites. The strategy refines forest structure mapping through three-dimensional (3D) modelling combined with empirical relationships, allowing improved estimation of maximum and predominant height, as well as foliage and crown cover at multiple scales. Tree stems (including those in the sub-canopy) were located using a height scaled crown openness index (HSCOI), which integrated the 3D density of canopy elements within the vertical profile into a two-dimensional spatial layer. The HSCOI modelling also facilitated the reconstruction of the 3D distribution of foliage and branches (of varying size and orientation) within the forest volume. ¶ Comparisons between forests at the Queensland and NE Victorian study sites indicated that accurate and consistent retrieval of cover and height metrics could be achieved at multiple scales, with the algorithms applicable for semi-automated use in other forests with similar structure. This information has facilitated interpretation and evaluation of Landsat imagery and ICESat satellite laser data for forest height and canopy cover retrieval. The development of a forest cover translation matrix allows a range of data and metrics to be compared at the plot scale, and has initiated the development of continuous transfer functions between the metrics and datasets. These data have been used subsequently to support interpretation of SAR data, by providing valuable input to 2D and 3D radar simulation models. Scale effects have been identified as being significant enough to influence national forest class reporting in more heterogeneous forests, thus allowing the most appropriate use and integration of remote sensed data at a range of scales. An empirically based forest minimum mapping area of 1 ha for reporting is suggested. The research has concluded that LiDAR can provide calibration information just as detailed and possibly more accurately than field measurements for many required forest attributes. Therefore the use of LiDAR data offers a unique opportunity to bridge the gap between accurate field plot structural information and stand to landscape scale sampling, to provide enhanced forest assessment in Australia.

Enhanced understanding of forest stocks and dynamics can be gained through improved forest measurement, which is required to assist with sustainable forest management decisions, meet Australian and international reporting needs, and improve research efforts to better respond to a changing climate. Integrated sampling schemes that utilise a multi-scale approach, with a range of data sourced from both field and remote sensing, have been identified as a way to generate the required forest information. Given the multi-scale approach proposed by these schemes, it is important to understand how scale potentially affects the interpretation and reporting of forest from a range of data. ¶ To provide improved forest assessment at a range of scales, this research has developed a strategy for facilitating tree and stand level retrieval of structural attributes within an integrated multi-scale analysis framework. The research investigated the use of fine-scale (~1m) airborne Light Detection and Ranging (LiDAR) data (1,125 ha in central Queensland, and 60,000 ha in NE Victoria) to calibrate other remotely sensed data at the two study sites. The strategy refines forest structure mapping through three-dimensional (3D) modelling combined with empirical relationships, allowing improved estimation of maximum and predominant height, as well as foliage and crown cover at multiple scales. Tree stems (including those in the sub-canopy) were located using a height scaled crown openness index (HSCOI), which integrated the 3D density of canopy elements within the vertical profile into a two-dimensional spatial layer. The HSCOI modelling also facilitated the reconstruction of the 3D distribution of foliage and branches (of varying size and orientation) within the forest volume. ¶ Comparisons between forests at the Queensland and NE Victorian study sites indicated that accurate and consistent retrieval of cover and height metrics could be achieved at multiple scales, with the algorithms applicable for semi-automated use in other forests with similar structure. This information has facilitated interpretation and evaluation of Landsat imagery and ICESat satellite laser data for forest height and canopy cover retrieval. The development of a forest cover translation matrix allows a range of data and metrics to be compared at the plot scale, and has initiated the development of continuous transfer functions between the metrics and datasets. These data have been used subsequently to support interpretation of SAR data, by providing valuable input to 2D and 3D radar simulation models. Scale effects have been identified as being significant enough to influence national forest class reporting in more heterogeneous forests, thus allowing the most appropriate use and integration of remote sensed data at a range of scales. An empirically based forest minimum mapping area of 1 ha for reporting is suggested. The research has concluded that LiDAR can provide calibration information just as detailed and possibly more accurately than field measurements for many required forest attributes. Therefore the use of LiDAR data offers a unique opportunity to bridge the gap between accurate field plot structural information and stand to landscape scale sampling, to provide enhanced forest assessment in Australia.

The canopy cover of the Pinus contorta forests of west-central Alberta, dictates colonization of the forest floor ground layer. This dynamic ground layer is a mosaic of feather mosses and reindeer lichens in a system driven by disturbance. In this project, anthropogenic was used to control canopy cover change and study its effects on the ground layer. Timber companies selectively mechanically thinned sections producing three experimental areas with uncut controls. Data were collected from 182, 6.5 m2 plots located in the four thinning areas. Six general areas of inquiry were posed around determining ground layer responses to canopy opening: 1) vegetation, 2) plant species richness, 3) plant abundance, 4) diaspore availability, 5) environmental limiting factors, 6) moss and lichen establishment. In 1997, three timber companies were involved in selective tree removal at three different stand percentages (20/40/60%), however, these were not consistent when measured in 2005. This variation in operational logging along with changes over the seven year time period, resulted in strong disparity for each of the thinning regimes. Percent canopy cover change for all thinned plots was ranked and three new groups created; least, moderate, most canopy change. These new groups formed the basis for the data presented in Chapter 3. The three thinning groups had little to no effect on species richness, but overall showed a small decrease from measurements taken pre-harvest. Numbers of locally rare species were similar to pre-harvest levels, but there were some gains and losses of species between pre-harvest and seven years post-harvest. In contrast to the lack of change in diversity, the abundance of dominant species and major vegetation components underwent dramatic changes. Dominant species of both vascular plants and bryophytes decreased with increasing canopy openness, with vascular plants being gradually affected while mosses were more affected at less intense canopy opening. Abundances of lichens showed no change. When measuring limiting factors (biotic and abiotic) for ground layer mosses and lichens, diaspores (spores and fragments) were plentiful in all stands, but differed in abundance at the micro-scale. The position of feather mosses and reindeer lichen in the forest floor mosaic appears to be due to an intermingling of environmental influences (at both the meso- and micro-scale). With less environmental constraints on lichens and the widespread availability of lichen fragments, lichens are more tolerant to the conditions evoked by thinning than are mosses. Mosses are more restricted by environmental conditions and have more constrained diaspore dispersal than lichens. Thus, mosses are more limited both by diaspore dispersal and by harsh environmental conditions in open canopy habitats. Whereas relative humidity (RH) did not differ at the stand level, moss dominated areas had higher RH no matter where they occurred, lichen-dominated areas did not--suggesting the moss occurrence is at least partially controlled by micro-scale level factors. Moss establishment is effected by the "ghosts" of past events and substrates. Mosses are widespread in formerly moss-dominated areas that contain organic substrates and high canopy cover. Lichen establishment is limited in previously moss-dominated areas. Species interactions weighed more heavily on moss establishment than on that of lichens. Therefore, the effects of canopy change on the ground layer are variable corresponding to moss decreases, but not lichens. Seven years post-harvest species diversity is unchanged, but vegetation, as a whole, has been affected.

Continental scale analysis of the savanna biome indicated that fire did not spread at tree canopy cover above 40%. This study investigates this relationship in a field study. It is possible that the type of tree (forest vs. savanna) may influence the amount of shade experienced by the understory and therefore this study also explores differences in LAI between congeneric pairs of forest and savanna tree species. Data were collected in two major South African savanna parks. Plots were set out to measure grass biomass in reference to canopy cover in both Kruger National Park (n=60) and the Hluhluwe-iMfolozi Game Reserve (n=82). Seven congeneric pairs were selected to compare leaf area and LAI between forest and savanna tree species using a destructive method. Against expectations, it was only when canopy cover reached 80% that grass fuel load was too low to support fire spread in all Kruger National Park plots (Pr=O) and 89% of the Hluhluwe-iMfolozi Game Reserve plots (Pr=0.11). No consistent, general relationships were evident with leaf area or LAI in comparisons between forest-savanna congeneric pairs. The significance of these findings and future direction is discussed.

>Magister Scientiae - MSc / The climate variability and climate change-induced events experienced worldwide have caused a significant decrease in the rainfall volume. South Africa is considered to be one of the driest countries in the world, as it receives an average annual rainfall that is lower than the global annual average. To sustain and grow the agricultural sector, South Africa supplements the low rainfall with its freshwater resources, for irrigation purposes. This action is necessary, especially for meeting the high water requirements of the South African fruit industry, as it is one of the major exporters of fruit in the world. Research has been conducted in an attempt to accurately quantify the water requirements of various fruits, which will assist farmers to save water, to increase their productivity and to managing their irrigation water. However, a knowledge of the water use, actual water consumption rates and the factors that drive them, is minimal and inadequate, and this has had a detrimental effect on the effective management of irrigation water and water allocation by the responsible stakeholders.

Urban trees are crucial to a healthy environment. The benefits range from good air quality to storm water management and public health. The aim of this thesis was to study urban trees in Umeå city. Umeå is in a process of densification and has a vision to increase in population to 200 000 by the year 2050. During densification, trees are often removed to make space for buildings and streets. To keep track of the trees in an urban area, an analysis of the share of canopy cover can be done. For this thesis, the city enter in Umeå has been analyzed to find out the share of trees, vegetation, imposturous ground, buildings, and water that makes up the land cover. This through a canopy cover analysis using the software i-Tree Canopy. The results show that the overall share of urban trees has decreased since 2007 and the share of buildings have increased, an evident effect of densification. In addition to analyzing canopy cover, the change in amount and location of municipally owned trees has also been analyzed. This analysis presented a contradictory view of urban trees, where the number of trees has increased. A reason for this could be that while the municipality has programs in place to plant and manage trees, privately owned trees are not being monitored. There are obstacles with the aim to increase the number of urban trees in a dense city. The increasing amount of imposturous ground and building makes the environment hard for trees to thrive in. The roots have not enough space to grow, and the trees are prone to damages. This results in trees that does not live very long before they have to be removed and replaced, which has negative effect on the environment. Preserving trees with large canopies and at the same time planting new ones are important parts in keeping a sustainable urban area. Analyzing canopy cover and the change over time is a way to learn and prepare for future urban planning in Umeå.

No description available.

<p>Worldwide amphibians and reptiles are declining with habitat fragmentation and destruction as the primary cause. Riparian areas are important for the herpetofauna, but as land is converted to agriculture or harvested for timber the areas are diminishing. The aim of this study was to examine amphibian and reptile abundance in relation to distance from water and in relation to habitat characteristics, foremost per cent deciduous trees. The survey was conducted during spring at six different locations, with continuous forest along streams or rivers, outside of Karlstad, Sweden. Animals were searched along four lines parallel to the water and each study area was visited five times. Statistical analyses were made for grass snake (<em>Natrix natrix</em>), common lizard (<em>Lacerta vivipara</em>) and frogs with joined data of common frog (<em>Rana temporaria</em>) and moor frog (<em>R. arvalis</em>). As expected both reptiles were positively correlated with per cent deciduous trees, with the strongest significance for the common lizard. For grass snake there was also a difference between survey periods, which might reflect the importance of weather. Frogs revealed no trends to trees, but there was a significant difference for habitat characteristics like amount woody debris and per cent bare ground. None of the species were correlated with distance from water which was surprising, especially for the frogs which is more dependent on water than the reptiles. Grass snakes hunt in the water, but the common lizard has no such associations to the water, yet the latter did reveal a slight trend towards being more numerous closer to the water. The causes behind lacking correlation to distance from water may be many, but water characteristics seem very important. Many amphibians prefer warm and calm ponds over running water that in general are colder and likely to inhabit more predators. It was assumed that the amphibians breed in the streams or rivers, but it is possible that other water bodies may have served as breeding sites, which mean the starting point was incorrect.</p>

Regenerating oak (Quercus spp.) is a problem on most intermediate to high-quality sites throughout the eastern US. Oak is often present in the overstory and abundant in the understory, but is absent from the midstory due to increased competition from less-valuable mesic species such as Liriodendron tulipifera and Acer rubrum. Red maple has expanded its range dramatically since fire suppression began in the 1930s, and is an important competitor of oak. To study relationships between oak and silvicultural treatments, an experiment was initiated in 1990 that included three northern red oak (Quercus rubra)-dominated stands and three red pine (Pinus resinosa) plantations in northern Lower Michigan. Areas of each stand were thinned to four levels of canopy cover in 1991: clearcut, 25% residual canopy, 75% residual canopy, and uncut control, with caged and uncaged northern red oak seedlings planted within each treatment. A thick midstory of red maple developed over the subsequent ten years, hindering development of advance oak regeneration. Low-intensity, early-spring prescribed fires were conducted on all stands in 2002 and 2008 in an effort to control red maple. Heights of planted red oak and naturally occurring red maple and oak regeneration in three size classes were measured before and after each fire with the objectives to: 1) Test the hypothesis that oak sprouts would have greater height growth after the 2008 prescribed burn than after the 2002 prescribed burn; 2) Test the hypotheses that (a) red maple stems would be reduced to a greater degree following the 2008 burn than following the 2002 burn, and that (b) the number of natural oak stems would be increased to a greater degree following the 2008 burn than following the 2002 burn; and 3) Evaluate the relationships between post-burn planted oak sprout height and pre-burn planted oak sprout height, fire temperature, and canopy cover. Following the second fire, planted oak sprouts increased in height rapidly in pine stands, where there was little red maple competition, but grew less rapidly in oak stands. Red maple densities decreased more following the first fire than the second fire. The hypothesis that natural oak regeneration stem densities would increase to a greater degree following the 2008 burn than following the 2007 burn was not supported. Pre-burn planted oak height was the best predictor of post-burn planted oak height.